Release fluid compositions

ABSTRACT

Use of release fluids or agents constituting hyperbranched polymers. The three-dimensional structure imparts characteristics that make the hyperbranched polymers useful in xerographic processes. The hyperbranched polymer release fluids or agents may be used with a fuser member having a substrate, an outer layer covering the substrate, and a release coating on the outer layer, wherein the release coating includes a hyperbranched polymer.

RELATED APPLICATIONS

The application is a Divisional of U.S. application Ser. No. 11/175,101,filed Jul. 5, 2005, which is expressly incorporated by reference.

BACKGROUND

The presently disclosed embodiments are directed to release fluids oragents that are useful in release coating in toner-based technologies.More particularly, the embodiments pertain to the use of hyperbranchedpolymers with three-dimensional structures in release fluids for animproved contact fusing system to fix toner images to a substrate.

In electrostatographic reproducing apparatuses, including digital, imageon image, and contact electrostatic printing apparatuses, a light imageof an original to be copied is typically recorded in the form of anelectrostatic latent image upon a photosensitive member and the latentimage is subsequently rendered visible by the application ofelectroscopic thermoplastic resin particles and pigment particles, ortoner. The residual toner image can be either fixed directly upon thephotosensitive member or transferred from the member to another support,such as a sheet of plain paper with subsequent fixing or fusing.

In order to fix or fuse the toner material onto a support memberpermanently by heat, it is usually necessary to elevate the temperatureof the toner material to a point at which the constituents of the tonermaterial coalese and become tacky. This heating action causes the tonerto flow to some extent into the fibers or pores of the support member.Thereafter, as the toner material cools, solidification of the tonermaterial causes the toner material to be bonded firmly to the supportmember.

Typically, the thermoplastic resin particles are fused to the substrateby heating to a temperature of from about 90 degrees Celsius to about200 degrees Celsius or higher, depending on the softening range of theparticular resin used in the toner. It may be undesirable, however, toincrease the temperature of the substrate substantially higher thanabout 250 degrees Celsius because the substrate may discolor or convertinto fire at such elevated temperatures, particularly when the substrateis paper.

Several approaches to thermal fusing of electroscopic toner images havebeen described. These methods include providing the application ofsubstantial heat and pressure concurrently by various means, includingfuser members such as a roll pair maintained in pressure contact, a beltmember in pressure contact with a roll, a belt member in pressurecontact with a heater, and the like. Heat can be applied by heating oneor both of the rolls, plate members, belt members, or the like. Thefuser member can be in the form of a roller, drum, belt, sheet, film,drelt (a hybrid between a roll and a belt), and the like. The fusing ofthe toner particles occurs when the proper combination of heat,pressure, and/or contact for the optimum time period are provided. Thebalancing of these variables to bring about the fusing of the tonerparticles can be adjusted to suit particular machines or processconditions.

During operation of a fusing system in which heat is applied to causethermal fusing of the toner particles onto a support, both the tonerimage and the support are passed through a nip formed between the rollpair, or plate or belt members. The concurrent transfer of heat and theapplication of pressure in the nip affect the fusing of the toner imageonto the support. It is important that minimal or no offset of the tonerparticles from the support to the fuser member takes place during normaloperations. Toner particles that offset onto the fuser member cansubsequently transfer to other parts of the machine or onto the supportin subsequent copying cycles, increasing the image background, andcausing inadequate copy quality, inferior marks on the copy,interference with the material being copied, and toner contamination ofother parts of the machine. Such problems, known as “hot offset,” occurwhen the temperature of the toner is increased to a point where thetoner particles liquefy and a splitting of the molten toner takes placewith a portion remaining on the fuser member. The hot offset temperatureor degradation of the hot offset temperature directly impacts therelease properties of the fuser member. Accordingly, it is desirable toprovide a fusing surface with low surface energy to provide thenecessary release. To ensure and maintain good release properties of thefuser member, release fluids may be applied to the fuser member duringthe fusing operation to prevent toner offset.

U.S. Pat. No. 4,257,699 to Lentz, the subject matter of which is herebyincorporated by reference in its entirety, discloses a fuser membercomprising at least one outer layer of an elastomer containing ametal-containing filler and use of a polymeric release agent.

U.S. Pat. No. 4,264,181 to Lentz et al., the subject matter of which ishereby incorporated by reference in its entirety, discloses a fusermember having an elastomer surface layer containing metal-containingfiller therein and use of a polymeric release agent.

U.S. Pat. No. 4,272,179 to Seanor, the subject matter of which is herebyincorporated by reference in its entirety, discloses a fuser memberhaving an elastomer surface with a metal-containing filler therein anduse of a mercapto-functional polyorganosiloxane release agent.

U.S. Pat. No. 5,401,570 to Heeks et al., the subject matter of which ishereby incorporated by reference in its entirety, discloses a fusermember comprised of a substrate and a silicone rubber surface layer overthe substrate containing a filler component, wherein the fillercomponent is reacted with a silicone hydride release agent.

U.S. Pat. No. 4,515,884 to Field et al., the subject matter of which ishereby incorporated by reference in its entirety, discloses a fusermember having a silicone elastomer-fusing surface, which is coated witha toner release agent, which includes an unblended polydimethylsiloxane.

Different types of release fluids or agents can be used to providesufficient release. However, the sufficiency of the release depends onthe selected release fluid or agent and an appropriate combination ofthe fuser member surface material and any filler to be incorporated intothe fuser member surface material. Despite using appropriatecombinations, however, commonly used release fluids or agents, such asthose including conventional linear polymers, sometimes still do notprovide sufficient release for the toner image.

One approach to the problem is through the use of polymeric releaseagents having functional groups, either at the chain-end or pendant tothe linear chain. The reactivity of functional groups with thesurfactants of the fuser member, such as long chain fluorinated acid,helps facilitate robust and uniform incorporation into the release fluidso that rapid wetting of the fluid onto a roller surface is promoted.The use of these polymeric agents, which interact with a fuser member toform a thermally stable, renewable self-cleaning layer having goodrelease properties for electroscopic thermoplastic resin toners, isdescribed in U.S. Pat. Nos. 4,029,827; 4,101,686; and 4,185,140, thedisclosures each of which are incorporated by reference herein in theirentirety. Disclosed in U.S. Pat. No. 4,029,827 is the use ofpolyorganosiloxanes having mercapto functionality as release agents.U.S. Pat. Nos. 4,101,686 and 4,185,140 are directed to polymeric releaseagents having functional groups such as carboxy, hydroxy, epoxy, amino,isocyanate, thioether and mercapto groups as release fluids. U.S. Pat.No. 5,716,747 discloses the use of fluorine-containing silicone fluidsfor use on fixing rollers with outermost layers of ethylenetetrafluoride perfluoro alkoxyethylene copolymer,polytetrafluoroethylene and polyfluoroethylene-propylene copolymer. U.S.Pat. No. 5,698,320 discloses the use of fluorosilicone polymers for useon fixing rollers with outermost layers of perfluoroalkoxy andtetra-fluoroethylene resins.

However, there are still some problems associated with the use of theabove release agents. Common problems include inducement of swelling offuser member surface coatings, insufficient wetting of fuser members,poor toner adhesion to the support, and poor interaction with thefillers in the fuser members. Additionally, various compositions thathave been proposed for treating fuser roll and belt substrates to impartrelease properties suffer from thermal instability when heated to fusingtemperatures, for example, about 150 degrees Celsius and above, forshort periods of time of, for example, about 0.5 seconds and longer.Thermal degradation of these release fluids or agents and relatedderivatives may result in the generation of volatile byproducts.

Thus, while known compositions and processes are suitable for theirintended purposes, there remains a need for improved release fluids oragents to help facilitate sufficient release of the fuser member andsubstantially prevent toner offset. For example, a need remains forrelease fluids or agents that react well with the surfaces commonly usedin fusing systems, without the problems mentioned above, includingsystems using solid ink jet transfix printing processes.

SUMMARY

According to aspects illustrated herein, there is provided a releasefluid comprising a hyperbranched polymer. The hyperbranched polymer hasa three-dimensional structure. One embodiment of the present inventionincludes a hyperbranched polymer that is poly(siloxysilane).

An embodiment may include: a fuser member comprising a substrate; anouter layer covering the substrate; and a release coating on the outerlayer, wherein the release coating includes a hyperbranched polymerwhich is the sol-gel product of structures represented by the followingFormula I:

[(OR₁)₃SiCH₂—]_(x)[(OR₂)₂(R₄)Si(CH₂—)]_(y)[(OR₃)(R₅)₂Si(CH₂—)]_(z)[(R₆)₃Si(CH₂—)]_(n)

where R₁, R₂, and R₃ are selected from the group consisting of H, CH₃,alkyl, aryl, alkylaryl, trimethylsilane, dimethylsilane, methylsilane, anonfunctional polysiloxane oligomer or polymer, or an amine-, mercapto-,or fluorine-containing polysiloxane oligomer or polymer; R₄, R₅, and R₆,are selected from the group consisting of CH₃, alkyl, aryl, alkylaryl,alkylamino, alkylmercapto, fluoroalkyl; x=0-400, y=0-400, z=0-400,n=0-400; x+y+z+n is selected so that the final sol-gel product achievesa fluid viscosity of from about 10 cS to about 1000 cS. Note that sincethe structures represented by Formula I are prepared by a hydrosilationreaction involving a silicone hydride and a vinyl group, some of theCH₂— groups in Formula I could be replaced by unreacted H or CH═CH₂. Insome embodiments, the composition of the outer layer may be selectedfrom the group consisting of a silicone elastomer, a fluorosiliconeelastomer, a fluoroelastomer, a fluorinated hydrocarbon polymer, afluorinated hydrocarbon and silicone polymer blend, silicone copolymers,and crosslinked blends of fluorinated hydrocarbon copolymers andsilicone copolymers. In a particular embodiment, R₁, R₂ and R₃ aremethyl or ethyl groups and R₄, R₅ and R₆ are methyl groups. The releasecoating may also further include a linear siloxane polymer eitherco-reacted in the sol-gel reaction with Formula I or blended with thesol-gel product of structures represented by Formula I.

Another embodiment may further include: an image forming apparatus forforming images on a recording medium comprising: a charge-retentivesurface to receive an electrostatic latent image thereon; a developmentcomponent to apply a developer material to the charge-retentive surfaceto develop the electrostatic latent image to form a developed image onthe charge-retentive surface; a transfer component to transfer thedeveloped image from the charge retentive surface to a copy substrate;and a fuser member component to fuse the transferred developed image tothe copy substrate, wherein the fuser member comprises: a substrate; anouter layer covering the substrate; and a release coating on the outerlayer; wherein the release coating includes a hyperbranched polymerwhich is the sol-gel product of structures represented by the followingFormula I:

[(OR₁)₃SiCH₂—]_(x)[(OR₂)₂(R₄)Si(CH₂—)]_(y)[(OR₃)(R₅)₂Si(CH₂—)]_(z)[(R₆)₃Si(CH₂—)]_(n)

where R₁, R₂, and R₃ are selected from the group consisting of H, CH₃,alkyl, aryl, alkylaryl, trimethylsilane, dimethylsilane, methylsilane, anonfunctional polysiloxane oligomer or polymer, or an amine-, mercapto-,or fluorine-containing polysiloxane oligomer or polymer; R₄, R₅, and R₆,are selected from the group consisting of CH₃, alkyl, aryl, alkylaryl,alkylamino, alkylmercapto, fluoroalkyl; x=0-400, y=0-400, z=0-400,n=0-400; x+y+z+n is selected so that the final sol-gel product achievesa fluid viscosity of from about 10 cS to about 1000 cS. Note that sincethe structures represented by Formula I are prepared by a hydrosilationreaction involving a silicone hydride and a vinyl group, some of theCH₂— groups in Formula I could be replaced by unreacted H or CH═CH₂.Again, in some embodiments, the composition of the outer layer may beselected from the group consisting of a silicone elastomer, afluorosilicone elastomer, a fluoroelastomer, a fluorinated hydrocarbonpolymer, a fluorinated hydrocarbon and silicone polymer blend, siliconecopolymers, and crosslinked blends of fluorinated hydrocarbon copolymersand silicone copolymers. In a particular embodiment, R₁, R₂ and R₃ aremethyl or ethyl groups and R₄, R₅ and R₆ are methyl groups. The releasecoating may also further include a linear siloxane polymer eitherco-reacted in the sol-gel reaction with Formula I or blended with thesol-gel product of structures represented by Formula I.

In embodiments, an outer layer comprising a fluoroelastomer may furtherbe selected from the group consisting of 1) copolymers of two ofvinylidene fluoride, hexafluoropropylene and tetrafluoroethylene; 2)terpolymers of vinylidene fluoride, hexafluoropropylene andtetrafluoroethylene; and 3) tetrapolymers of vinylidene fluoride,hexafluoropropylene, tetrafluoroethylene, and a cure site monomer.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference may behad to the accompanying figures.

FIG. 1 is a schematic illustration of an image apparatus in accordancewith the present invention.

FIG. 2 is an enlarged, side view of an embodiment of a fuser member,showing a fuser member with a substrate, intermediate layer, outerlayer, and release coating layer.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings, which form a part hereof and which illustrate severalembodiments of the present invention. It is understood that otherembodiments may be utilized and structural and operational changes maybe made without departure from the scope of the present invention.

Embodiments of the present invention relate to fuser members having arelease fluid or agent in combination therewith. The fuser member can bein the form of a roller, drum, belt, sheet, film, drelt (a hybridbetween a roll and a belt), and the like. The fuser member may have anouter layer in combination with a hyperbranched polymer release fluid,for example, a release fluid including poly(siloxysilane). Thecombination, in embodiments, allows for sufficient wetting of the fusermember to facilitate sufficient release of the fuser member and preventtoner offset. While most polymers are not temperature stable in theranges required for the described applications, release fluidscontaining silicon-based and fluorinated polymers are fluids that maywithstand such temperatures.

Hyperbranched poly(siloxysilane)s and poly(alkoxysilane)s are mostlyformed through a hydrosilation reaction involving a silicone hydride anda vinyl group. The synthesis of these polymers may be achieved ingreater proportions by using a divergent method involving repetitiveaddition of a stoichiometric amount of monomer in a process designed tomimic generation growth. Another approach involves changing the ratio ofthe AB_(x) monomer to be added to the B mono-functional molecule. Yetanother approach involves slow monomer addition or seededpolymerizations in which the monomer is slowly added to a “core” orpre-formed polymer, with the post-addition of a fresh catalyst, or theuse of new AB₃, AB₄ and AB₆ monomers or even the post-addition of afresh monomer. These approaches to building hyperbranched silicone-basedpolymers are described in The Journal of Polymer Science: Part A PolymerChemistry Vol. 37, 3193-3201 (1999), Intramolecular Cyclization in thePolymerization of AB_(x) Monomers: Approaches to the Control ofMolecular Weight and Polydispersity in Hyperbranched Poly(siloxysilane).

An example may include monomer 3, an AB₂ monomer that is readilyobtained from dichlorovinylmethylsilane (1) and chlorodimethylsilane (2)in a process that might be easily scaled in accordance with Scheme 1:

Addition of a catalytic amount of platinum to monomer 3, as shown above,causes the formation of hyperbranched poly(siloxysilane) throughrepeated hydrosilation reactions. After the desired molecular weight isachieved, the polymerization reaction may be halted by introducing amonomer containing no hydride functionality (such as monomer 3 a, shownbelow) to inhibit further hydrosilation:

The resulting hyperbranched poly(siloxysilane) has numerous advantagesincluding, low viscosity with low volatility, higher reactivity,improved surface coverage and wettability for a variety of materials.Hyperbranched polymers have a lower viscosity as compared to linearpolymers of similar molecular weight due to higher chain mobility andlower entanglements. For example, a release fluid that does not includehyperbranched polymers may have a viscosity in the range of about 200 to1000 centistokes (cS). If a hyperbranched polymer is included in thecomposition, however, the viscosity is reduced to a range of about 100to 600 cS. In addition, the hyperbranched poly(siloxysilane) has ahigher molecular weight that is desirable in creating a barrier orrelease layer thicker than those related to linear, low-viscosityrelease fluids.

In one embodiment of the hyperbranched polymer, comprised ofpoly(siloxysilane), the three-dimensional structure of the polymerenhances a contact fusing system because it allows the release fluid tospread sufficiently over the fuser member, and thus, increases fusermember life. The three-dimensional structure of poly(siloxysilane) alsoprovides improved properties and performance to the release fluids, byimparting improved solubility and compatibility with other polymers inthe fusing system. The hyperbranched poly(siloxysilane) polymer alsoproduces a release coating that has reduced viscosity without thevolatility associated with typical low viscosity, which improves theease of processing and enhances wetting coverage. The lower viscosityallows improved metering for the release fluid as compared to a linearpolydimethylsiloxane (PDMS) of similar molecular weight.

Referring to FIG. 1, in a typical electrostatic reproducing apparatus, alight image of an original to be copied is recorded in the form of anelectrostatic latent image upon a photosensitive member and the latentimage is subsequently rendered visible by the application ofelectroscopic thermoplastic resin particles which are commonly referredto as toner. Specifically, photoreceptor 10 is charged on its surface bymeans of a charger 12 to which a voltage has been supplied from powersupply 11. The photoreceptor 10 is then imagewise exposed to light froman optical system or an image input apparatus 13, such as a laser andlight emitting diode, to form an electrostatic latent image on thephotoreceptor 10. Generally, the electrostatic latent image is developedby bringing a developer mixture from developer station 14 into contactherewith. Development can be effected by use of a magnetic brush, powdercloud, or other known development process. A dry developer mixtureusually comprises carrier granules having toner particles adheringtriboelectrically thereto. Toner particles are attracted from thecarrier granules to the latent image forming a toner powder image.Alternatively, a liquid developer material may be employed, whichincludes a liquid carrier having toner particles dispersed therein. Theliquid developer material is advanced into contact with theelectrostatic latent image and the toner particles are deposited thereonin image configuration.

After the toner particles have been deposited on the photoconductivesurface, in image configuration, they are transferred to a copy sheet 16by transfer means 15, which can be pressure transfer or electrostatictransfer. Alternatively, the developed image can be transferred to anintermediate transfer member, or bias transfer member, and subsequentlytransferred to a copy sheet. Examples of copy substrates include paper,transparency material such as polyester, polycarbonate, or the like,cloth, wood, or any other desired material upon which the finished imagewill be situated.

After the transfer of the developed image is completed, copy sheet 16advances to fusing station 19, depicted in FIG. 1 as fuser roll 20 andpressure roll 21 (although any other fusing member components such asfuser belt in contact with a pressure roll, fuser roll in contact withpressure belt, and the like, are suitable for use with the presentapparatus), wherein the developed image is fused to copy sheet 16 bypassing copy sheet 16 between the fusing and pressure members, therebyforming a permanent image. Alternatively, transfer and fusing can beeffected by a transfix application. Photoreceptor 10, subsequent totransfer, advances to cleaning station 17, wherein any toner left onphotoreceptor 10 is cleaned therefrom by use of a blade (as shown inFIG. 1), brush, or other cleaning apparatus.

FIG. 2 is an enlarged schematic view of an embodiment of a fuser member,demonstrating the various possible layers. As shown in FIG. 2, substrate1 includes an intermediate layer 2. Intermediate layer 2 can be, forexample, a rubber such as silicone rubber or other suitable rubbermaterial. On the intermediate layer 2 is positioned an outer layer 3.Positioned on the outer layer 3 is an outermost release layer 4including the hyperbranched polymer. The outer layer composition may beselected from the group consisting of a silicone elastomer, afluorosilicone elastomer, a fluoroelastomer, a fluorinated hydrocarbonpolymer, a fluorinated hydrocarbon and silicone polymer blend, siliconecopolymers, and crosslinked blends of fluorinated hydrocarbon copolymersand silicone copolymers. The thickness of the outer layer of the fusermember may be from about 1 to about 50 micrometers, or from about 5 toabout 20 micrometers.

Examples of the outer surface of the fuser system members includefluoroelastomers. Specifically, suitable fluoroelastomers are thosedescribed in detail in U.S. Pat. Nos. 5,166,031, 5,281,506, 5,366,772and 5,370,931, together with U.S. Pat. Nos. 4,257,699, 5,017,432 and5,061,965, the disclosures each of which are incorporated by referenceherein in their entirety. As described therein, these elastomers arefrom the class of 1) copolymers of vinylidenefluoride andhexafluoropropylene; 2) terpolymers of vinylidenefluoride,hexafluoropropylene and tetrafluoroethylene; and 3) tetrapolymers ofvinylidenefluoride, hexafluoropropylene, tetrafluoroethylene and curesite monomer, are known commercially under various designations as VITONA®, VITON B®, VITON E®, VITON E 60C®, VITON E430®, VITON 910®, VITONGH®; VITON GF®; and VITON ETP®. The VITON® designation is a Trademark ofE.I. DuPont de Nemours, Inc. The cure site monomer can be4-bromoperfluorobutene-1,1,1-dihydro-4-bromo-perfluorobutene-1,3-bromoperfluoro-propene-1,1,1-dihydro-3-bromoperfluoro-propene-1,or any other suitable, known cure site monomer commercially availablefrom DuPont. Other commercially available fluoropolymers include FLUOREL2170®, FLUOREL 2174®, FLUOREL 2176®, FLUOREL 2177® and FLUOREL LVS 76®,FLUOREL® being a Trademark of 3M Company. Additional commerciallyavailable materials include AFLAS™ a poly(propylenetetra-fluoroethylene)and FLUOREL II® (LII900) apoly(propylene-tetrafluoroethylene-vinylidenefluoride) both alsoavailable from 3M Company, as well as the Tecnoflons identified asFOR-60KIR®, FOR-LHF®, NM® FOR-THF®, FOR-TFS®, TH®, and TN505®, availablefrom Montedison Specialty Chemical Company.

The fluoroelastomers VITON GH® and VITON GF® have relatively low amountsof vinylidenefluoride. The VITON GF® and Viton GH® have about 35 weightpercent of vinylidenefluoride, about 34 weight percent ofhexafluoropropylene and about 29 weight percent of tetrafluoroethylenewith about 2 weight percent cure site monomer.

The amount of fluoroelastomer compound in solution in the outer layersolutions, in weight percent total solids, is from about 10 to about 25percent, or from about 16 to about 22 percent by weight of total solids.Total solids as used herein include the amount of fluoroelastomer,dehydrofluorinating agent and optional adjuvants and fillers, includingmetal oxide fillers. In addition to the fluoroelastomer, the outer layermay comprise a fluoropolymer or other fluoroelastomer blended with theabove fluoroelastomer. Examples of suitable polymer blends include theabove fluoroelastomer, blended with a fluoropolymer selected from thegroup consisting of polytetrafluoroethylene and perfluoroalkoxy. Thefluoroelastomer can also be blended with non-fluorinated ethylene ornon-fluorinated propylene.

An inorganic particulate filler may be used in connection with the outerlayer, in order to provide anchoring sites for the functional groups ofthe release fluid. Some suitable fillers include, for example, copperoxide, aluminum oxide, lead oxide, and zinc oxide. However, a filler isnot necessary for use with all fuser systems, such as one that usesfluorosilicone as the release fluid.

Optional intermediate adhesive layers and/or intermediate polymer orelastomer layers may be applied to achieve desired properties andperformance objectives of the embodiments of the present invention. Theintermediate layer may be present between the substrate and the outerfluoroelastomer surface. An adhesive intermediate layer may be selectedfrom, for example, epoxy resins and polysiloxanes. Examples of suitableintermediate layers include silicone rubbers such as room temperaturevulcanization (RTV) silicone rubbers; high temperature vulcanization(HTV) silicone rubbers and low temperature vulcanization (LTV) siliconerubbers. These rubbers are known and readily available commercially suchas SILASTIC® 735 black RTV and SILASTIC 732 RTV, both from Dow Corning;and 106 RTV Silicone Rubber and 90 RTV Silicone Rubber, both fromGeneral Electric. Other suitable silicone materials include thesiloxanes (such as polydimethylsiloxanes); fluorosilicones such asSilicone Rubber 552, available from Sampson Coatings, Richmond, Va.;liquid silicone rubbers such as vinyl crosslinked heat curable rubbersor silanol room temperature crosslinked materials; and the like. Anotherspecific example is Dow Corning Sylgard 182.

There may also be provided an adhesive layer between the substrate andthe intermediate layer. There may also be an adhesive layer between theintermediate layer and the outer layer. In the absence of anintermediate layer, the outer layer may be bonded to the substrate viaan adhesive layer. The thickness of the intermediate layer is from about0.5 to about 20 mm, or from about 1 to about 5 mm.

The release fluids or agents described herein are provided onto theouter layer of the fuser member via a delivery mechanism such as adelivery roll. The delivery roll is partially immersed in a sump, whichhouses the release fluid or agent.

The release fluids or agents, constituting hyperbranched polymers, arerenewable in that the release fluid or agent is housed in a holding sumpand provided to the fuser roll when needed, optionally by way of arelease fluid donor roll in an amount of from about 0.1 to about 20mg/copy, or from about 1 to about 12 mg/copy. The system by which fuserrelease fluid is provided to the fuser roll via a holding sump and,optionally, a donor roll is well known. The release fluid may be presenton the fuser member surface in a continuous or semi-continuous phase.The release fluid in the form of a film is in a continuous phase andcontinuously covers the fuser member.

Examples of suitable hyperbranched polymers for the release fluidsinclude poly(siloxysilane), wherein the polymer includes 250-300silicone atoms. In embodiments, examples of hyperbranchedpoly(siloxysilane) release coating includes a hyperbranched polymerwhich is the sol-gel product of structures represented by the followingFormula I:

[(OR₁)₃SiCH₂—]_(x)[(OR₂)₂(R₄)Si(CH₂—)]_(y)[(OR₃)(R₅)₂Si(CH₂—)]_(z)[(R₆)₃Si(CH₂—)]_(r)

where R₁, R₂, and R₃ are selected from the group consisting of H, CH₃,alkyl, aryl, alkylaryl, trimethylsilane, dimethylsilane, methylsilane, anonfunctional polysiloxane oligomer or polymer, or an amine-, mercapto-,or fluorine-containing polysiloxane oligomer or polymer; R₄, R₅, and R₆,are selected from the group consisting of CH₃, alkyl, aryl, alkylaryl,alkylamino, alkylmercapto, fluoroalkyl; x=0-400, y=0-400, z=0-400,n=0-400; x+y+z+n is selected so that the final sol-gel product achievesa fluid viscosity of from about 10 cS to about 1000 cS. Note that sincethe structures represented by Formula I are prepared by a hydrosilationreaction involving a silicone hydride and a vinyl group, some of theCH₂— groups in Formula I could be replaced by unreacted H or CH═CH₂. Insome embodiments, the composition of the outer layer may be selectedfrom the group consisting of a silicone elastomer, a fluorosiliconeelastomer, a fluoroelastomer, a fluorinated hydrocarbon polymer, afluorinated hydrocarbon and silicone polymer blend, silicone copolymers,and crosslinked blends of fluorinated hydrocarbon copolymers andsilicone copolymers. In a particular embodiment, R₁, R₂ and R₃ aremethyl or ethyl groups and R₄, R₅ and R₆ are methyl groups. The releasecoating may also further include a linear siloxane polymer eitherco-reacted in the sol-gel reaction with Formula I or blended with thesol-gel product of structures represented by Formula I.

A specific example of a poly(siloxysilane) group in the hyperbranchedpolymer release fluid may be one wherein the hyperbranched polymer hasapproximately 250 silicone atoms, and corresponds to a viscosity of 300cS.

A specific example of a poly(siloxysilane) release fluid is one havingthe following Formula II:

where R represents a further chain extension. In the above formula, thetotal length of the polymer chain includes approximately 150-300silicone atoms, which corresponds to a viscosity of 300 cS. In otherembodiments, the poly(siloxysilane) release fluid has a viscosity offrom about 10 to about 1000 cS, or from about 100 to about 600 cS.

In embodiments, the hyperbranched polymer containing a siloxy backchainwith pendant R groups of Formulas I or II can be present in anon-functional or organofunctional release fluid. In embodiments, thepoly(siloxysilane) polymer containing pendant R groups as in Formulas Ithrough II above, may be present in the release fluid in amounts of formabout 1 to about 100 percent, 1 to about 50 percent, or from about 1 toabout 25 percent, or about 15 percent. However, the above formulas canalso be used in non-blended form where they would encompass 100 percentof the release fluid.

The hyperbranched polymer release fluid or agent can be prepared as acopolymer with a functional release agent such as an amine-functionalPDMS via copolymerization of amine-containing silane monomers or cyclicswith dichloro-containing silane monomers or cyclics. For the case of acopolymer of alkyl and amine pendant groups, the amine groups arepresent at a level that ranges from 0.01 percent to about 2 percent orfrom about 0.05 percent to about 1 percent. The alkyl functional groupsare present at a level which ranges from about 98 percent to about 99.99percent or from about 99 percent to about 99.95 percent.

Alternatively, the hyperbranched polymer can be prepared as a releasefluid through copolymerization with linear polymers. For the blend ofhyperbranched and linear polymers, the linear polymers can be present ata level which ranges from about 25 percent to about 90 percent or fromabout 50 percent to about 75 percent. The hyperbranched polymers arepresent at a level which ranges from about 10 percent to about 75percent or from about 25 percent to about 50 percent. The linearpolymers may be copolymerized with the hyperbranched polymer accordingto the general viscosity equation:

lnη_(Blend)=φ_(component1)lnη_(component1)+φ_(component2)lnη_(component2)+. . . +φ_(componentn)lnη_(componentn).

In another embodiment, a blend of about 1 percent to about 50 percent,or about 1 percent to about 25 percent of a hyperbranched polymer, suchas a poly(siloxysilane) polymer in a functional or non-functionalsilicone fluid, can be used to combine the advantages of both types ofindividual fluids. For example, in a blend of hyperbranched and linearpolymers, the resulting release fluid or agent can facilitate reactivitywith the fluoroelastomer substrate while a physical or chemicalcompatibility in the fluid contributes to excellent surface wettingcharacteristics. The poly(siloxysilane) release fluid can be blendedwith a non-functional silicone agent, such as a non-functional PDMS.

A non-functional agent, as used herein, refers to agents that do notinteract or chemically react with the surface of the fuser member orwith fillers on the surface. A functional agent, as used herein, refersto a release fluid having functional groups which chemically react withthe fillers present on the surface of the fuser member, so as to reducethe surface energy of the fillers and to provide better release of tonerparticles from the surface of the fuser member. If the surface energy isnot reduced, the toner particles will tend to adhere to the fuser rollsurface or to filler particles on the surface of the fuser roll, whichwill result in copy quality defects. The release fluid may be used withboth functional and non-functional agents, depending on the fusersurface.

In the above embodiments, the various R groups pendant to the siloxybackchain interact to fold the polymer into a three-dimensionalstructure. The blending of the hyperbranched polymer with linearpolymers imparts a different three-dimensional structure. The resultingthree-dimensional structure is different from the resulting structurefrom cross-linking linear polymers, which remains linear. Threedimensional or hyperbranched silicone fluids may have a competitive andfunctional advantage over conventional linear fluids, both inxerographic and direct marking printing systems.

All the patents and applications referred to herein are herebyspecifically, and totally incorporated herein by reference in theirentirety in the instant specification.

The following Examples further define and describe embodiments of thepresent invention. Unless otherwise indicated, all parts and percentagesare by weight.

EXAMPLES Example I Poly(siloxysilane) Release Fluid

A Poly(siloxysilane) Release Fluid is synthesized in a manner describedherein, or by other suitable means. The resulting polymer isapproximately 300 cs and contains amine functionality of 1.0 mole %amine relative to the silicon atoms in the concentrated structure. Thisconcentrated amine-functional hyperbranched polymer is then blended 1:9with a non-functional linear PDMS, which also has a viscosity of 300 cs.The resulting fluid is 300 cs and has an amine functionality of 0.1 molepercent. The resulting fluid can then be utilized as a release agent ina fuser subsystem or offset process transfix subsystem exhibitingenhanced release performance as compared to other release agentcompositions commonly used in the art.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Variouspresently unforeseen or unanticipated alternatives, modifications,variations or improvements therein may be subsequently made by thoseskilled in the art which are also intended to be encompassed by thefollowing claims.

1. A release fluid comprising a combination of a linear polymer and ahyperbranched polymer which is the product of structures represented bythe following Formula I:[(OR₁)₃SiCH₂—]_(x)[(OR₂)₂(R₄)Si(CH₂—)]_(y)[(OR₃)(R₅)₂Si(CH₂—)]_(z)[(R₆)₃Si(CH₂—)]_(n)wherein R₁, R₂, and R₃ are selected from the group consisting of H, CH₃,alkyl, aryl, alkylaryl, trimethylsilane, dimethylsilane, methylsilane, apolysiloxane oligomer or polymer, or an amine-, mercapto-, orfluorine-containing polysiloxane oligomer or polymer; R₄, R₅, and R₆,are selected from the group consisting of CH₃, alkyl, aryl, alkylaryl,alkylamino, alkylmercapto, fluoroalkyl; x=0-400, y=0-400, z=0-400,n=0-400; and x+y+z+n is selected so that the final product achieves afluid viscosity of from about 10 cSt to about 1000 cSt at roomtemperature, and further wherein the linear polymer is present in anamount of from about 25 percent to about 90 percent and thehyperbranched polymer is present in an amount of from about 10 percentto about 75 percent of the release fluid, wherein said hyperbranchedpolymer reduces viscosity of the release fluid to substantially preventtoner offset.
 2. The release fluid of claim 1, wherein the linearpolymer is present in an amount of from about 50 percent to about 75percent of the release fluid.
 3. The release fluid of claim 1, whereinthe hyperbranched polymer is present in an amount of from about 25percent to about 50 percent of the release fluid.
 4. The release fluidof claim 1, wherein the linear polymer is present in an amount of fromabout 50 percent to about 75 percent of the release fluid and thehyperbranched polymer is present in an amount of from about 25 percentto about 50 percent of the release fluid.
 5. The release fluid of claim1, wherein the linear polymer is copolymerized with the hyperbranchedpolymer according to the following equation:lnη_(Blend)=φ_(component1)lnη_(component1)+φ_(component2)lnη_(component2)+. . . +φ_(componentn)lnη_(componentn).
 6. The release fluid of claim 1,wherein the hyperbranched polymer is selected from the group consistingof poly(siloxysilane) and poly(alkoxysilane).
 7. The release fluid ofclaim 1 having a viscosity of from about 10 cSt to about 1000 G cSt atroom temperature.
 8. A release fluid comprising at least one linearpolymer and at least one hyperbranched polymer, and further wherein theat least one linear polymer is present in an amount of from about 25percent to about 90 percent and the at least one hyperbranched polymeris present in an amount of from about 10 percent to about 75 percent ofthe release coating and said hyperbranched polymer reduces viscosity ofthe release fluid to substantially prevent toner offset.
 9. The releasefluid of claim 7, wherein the linear polymer is present in an amount offrom about 50 percent to about 75 percent of the release fluid.
 10. Therelease fluid of claim 7, wherein the hyperbranched polymer is presentin an amount of from about 25 percent to about 50 percent of the releasefluid.
 11. The release fluid of claim 7, wherein the linear polymer ispresent in an amount of from about 50 percent to about 75 percent of therelease fluid and the hyperbranched polymer is present in an amount offrom about 25 percent to about 50 percent of the release fluid.
 12. Therelease fluid of claim 7, wherein the linear polymer is copolymerizedwith the hyperbranched polymer according to the following equation:lnη_(Blend)=φ_(component1)lnη_(component1)+φ_(component2)lnη_(component2)+. . . +φ_(componentn)lnη_(componentn)
 13. The release fluid of claim 7,wherein the hyperbranched polymer is selected from the group consistingof poly(siloxysilane) and poly(alkoxysilane).
 14. The release fluid ofclaim 7 having a viscosity of from about 10 cSt to about 1000 cSt atroom temperature.
 15. A release fluid comprising a copolymer of afunctional release agent and a hyperbranched polymer which is theproduct of structures represented by the following Formula I:[(OR₁)₃SiCH₂—]_(x)[(OR₂)₂(R₄)Si(CH₂—)]_(y)[(OR₃)(R₅)₂Si(CH₂—)]_(z)[(R₆)₃Si(CH₂—)]_(n)wherein R₁, R₂, and R₃ are selected from the group consisting of H, CH₃,alkyl, aryl, alkylaryl, trimethylsilane, dimethylsilane, methylsilane, apolysiloxane oligomer or polymer, or an amine-, mercapto-, orfluorine-containing polysiloxane oligomer or polymer; R₄, R₅, and R₆,are selected from the group consisting of CH₃, alkyl, aryl, alkylaryl,alkylamino, alkylmercapto, fluoroalkyl; x=0-400, y=0-400, z=0-400,n=0-400; and x+y+z+n is selected so that the final product achieves afluid viscosity of from about 10 cSt to about 1000 cSt at roomtemperature, and further wherein the hyperbranched polymer is present inan amount of from about 25 percent to about 50 percent of the releasefluid, wherein said hyperbranched polymer reduces viscosity of therelease fluid to substantially prevent toner offset.
 16. The releasefluid of claim 15, wherein the hyperbranched polymer is present in anamount of from about 25 percent to about 50 percent of the releasefluid.
 17. The release fluid of claim 15, wherein the hyperbranchedpolymer is selected from the group consisting of poly(siloxysilane) andpoly(alkoxysilane).
 18. The release fluid of claim 15 having a viscosityof from about 10 cSt to about 1000 cSt at room temperature.
 19. Therelease fluid of claim 15, wherein the functional release agent is anamine-functional polydimethylsiloxane.
 20. The release fluid of claim16, wherein the amine groups are present at a level that ranges fromabout 0.01 percent to about 2 percent in the copolymer.